1. Field of the Invention
The present invention relates to a tilt-trim device for a marine propulsion unit.
2. Description of the Related Art
Examples of tilt-trim devices for marine propulsion units include a tilt-trim device of an outboard motor. The outboard motor includes a propulsion unit comprising a propeller and an engine, supported axially by a swivel bracket such that the horizontal swinging movement is allowed, with the swivel bracket supported by a clamp bracket such that the vertical tilting movement is allowed, with the clamp bracket gripping a hull. A tilt-trim device is provided between the clamp bracket and the swivel bracket such that the motive power is generated by the telescopic motion of a hydraulic cylinder of the tilt-trim device. The propulsion unit and the swivel bracket are tilted vertically with respect to the clamp bracket so as to allow the tilt operation or the trim operation of the propulsion unit.
The above-described hydraulic cylinder device has a rod guide fixed to an end of the cylinder. And a piston fixed to one end portion of a piston rod is freely slidably disposed within the cylinder and in addition a hydraulic fluid is filled therein. In addition, the piston rod passes through a rod guide.
Generally, the cylinder of the hydraulic cylinder device is cast-molded using an aluminum alloy. Also, generally, the fixing of the rod guide to the end portion of the cylinder is performed by bringing an internal thread formed in the inner periphery of the end portion of the cylinder and an external thread formed on the outer periphery of the rod guide into engagement with each other as shown in, for example, Japanese Utility Model Application Publication (JP-Y) No. 5-3761.
Since, as described above, the rod guide is fixed to the inner periphery of the end portion of the cylinder by the thread connection, the mounting operation for the rod guide becomes inconveniently complex.